The present invention relates to check valves, and to pump assemblies and condiment dispensing systems employing such check valves. More particularly, the present invention relates to check valves which are straight forward in construction, easy to manufacture, and effective and durable in use, for example, in combination and conjunction with pump assemblies, such as those used in dispensing condiments and the like.
The typical condiment dispensing system involves a supply of condiment to be dispensed; a pump mechanism, such as a diaphragm pump, used to pump the condiment from the condiment supply; and to a valved dispensing conduit through which the pumped condiment is passed for use. The valve or valves included in the valved dispensing conduit are activated, as desired, to release a quantity of condiment from the dispensing system for use.
Check valves are normally used in combination with the pumping mechanism to provide for effective and efficient pumping of condiment from the condiment supply to the valved dispensing conduit. Examples of check valves which are typically used include so-called "flapper" valves and so-called "ball" valves.
The flapper valves typically involve a substantially flat valve element which is pivotably movable so as to be over or away from an opening in a conduit. Such flapper valves have certain disadvantages. For example, the durability of such valves is a concern, particularly in operations, such as condiment dispensing systems, where the check valve is repeatedly and frequently opened and closed. Because the flapper valve element typically is positioned on top of the opening to prevent flow, as the valve element wears, the valve becomes susceptible to blow-through, that is material passes across the valve when the valve is nominally closed so that the valve becomes ineffective to prevent the flow of material, as desired. In addition, if the flapper valve element is connected in an unbiased manner, a substantial and disadvantageous time delay in valve closing can occur, thus reducing the efficiency of the pump mechanism. On the other hand, if the flapper valve element is connected so as to have a "closed-position" bias, the biasing member, often a spring-adds complexity to the valve, increases the risk of mechanical failure and often occupies a portion of the conduit and thereby, at least to some extent, restricts material flow through the conduit when such flow is desired.
The ball valves typically used as check valves involve a spheroidal ball which can be positioned in a valve seat to prevent material flow. The ball remains located in the conduit, downstream of the seat, when material flow is to be allowed through the conduit. Such valves also have certain disadvantages. For example, the ball tends to become worn and/or wear the valve seat so that the valve becomes less and less effective over time, particularly in operations which the valve is opened and closed frequently. Also, even when the ball is away from the seat to allow material flow, the ball itself acts as an impediment to the flow of material. Springs and/or other biasing members may be used in ball values, but have substantially the same disadvantages discussed above with regard to flapper values.
Both of these typically used valves have substantial difficulties when the material being processed, for example, the condiment to be dispensed, includes particles or particulate material. The particulate material tends to adversely affect the seating of the valve element, thereby rendering the valve ineffective in preventing material flow, when such prevention is desired.
It would be advantageous to provide new check valves which overcome one or more of the problems of the prior check valves, for example, as described above.